1991 MS1 Idle Problem - help!
 

Hello all,

First post on here, Ive been lurking for a while now though.

I have very recently built my MS1 V3.0 for my 1991 MX-5, below is a picture of my board - before I fitted the Perez improved spark mod.

http://img442.imageshack.us/img442/1850/dscf5903.th.jpg

I am currently running NA, will be fitting a Mini Cooper M45 supercharger in the near future.

I have loaded the basemap from DIYautotune and set a reasonable AFR table, I have also fitted an LC-1 with gauge. I have matched the ignition timing in Tunerstudio.

My problem is with the idle, I have copied settings I found on DIYautotune for PWM idle at the bottom of the page here How to MegaSquirt your Mazda Miata except I have used closed loop only instead of warmup only, as warmup only was causing the revs to rise when warming.

What currently happens is that the engine idles fine, as the coolant temperature increases, the revs gradually drop to my specified hot idle speed which is as expected, however, if I rev the engine slightly when its hot, the revs rise, but never fall again to the warm idle speed, they will stay around 1800rpm. If I switch the engine off and back on again, the idle immediately returns to 900rpm (my hot idle speed). Also, if I unplug the ICV when it is idling at 1800rpm, this has no effect. I have tried turning the bleed screw clockwise a fair amount and anticlockwise to no effect - other than difficulty starting the engine.

What is causing the revs to stick at 1800rpm when I rev the engine from idle? Any comments/suggestions welcome

Cheers

try the settings from the MSPNP base map.

MSPNP basemap is loaded